Process for producing liquid crystal of desired properties by mixing together at least two still rod-shaped polymers of narrow molecular weight distributions and different weight-average molecular weights having chiral side chain groups

ABSTRACT

A process to produce a polymer liquid crystalline composition having temperature dependency of desired circular polarization selective reflection wave length property by only mixing two or more kinds of starting materials having different weight-average molecular weight comprising, mixing two or more kinds of rigid rodlike helical polymers with chiral side chains having different weight-average molecular weight synthesized from same molecules and having same repeating unit whose molecular weight distribution defined by the ratio of weight average molecular weight/number average molecular weight is from 1.00 to 1.25, and controlling weight average molecular weight, number average molecular weight and molecular weight distribution by mixing ratio.

FIELD OF THE INVENTION

The present invention relates to a process for producing polymersshowing desired liquid crystal property, in particular, showingcholesteric liquid crystal property by simply mixing rigid rodlikepolymers having chiral side chains with narrow molecular weightdistributions and different weight-average molecular weights whosemolecular weight distribution and molecular weight are previously fixed.

DESCRIPTION OF THE PRIOR ART

The inventors of the present invention considered that the polymer for adesired object can be optinally produced by fractionating rigid rodlikehelical optically active polysilanes with bimodal molecular weightdistribution having optically active alkyl side chain group, which has abranching structure at β site, into polymer with specific molecularweight range and by observing the property of the fractionated polymer,and, found out a unique liquid crystal property by observing chemicalproperty change along with the temperature change of the polymer whosemolecular weight is relatively small (Japanese Patent Laid-OpenPublication 2001-164251, published on Jun. 19, 2001).

That is, the inventors of the present invention found that polysilanes,which show cholesteric liquid crystal property, has a characteristic toalter circular polarization wave length property largely by differenceof molecular weight and by temperature change.

Further, the inventors of the present invention synthesizedpoly(n-decyl-(s)-2-methylbutylsilane) (PD2 MBS) by Wurtz typecondensation process, fractionated it to the sample whose moleculardistribution is from 1.05 to 1.20 and weight-average molecular weight(Mw) is from 20,000 to 50,000, and the liquid crystal constitution ofthe obtained sample was observed by a polarization microscope and theidentification of liquid crystal phase was carried out by X ray (smallangle X ray structural diffraction, wide angle X ray diffraction).

Then, the inventors of the present invention carried out the structuralobservation of PD2 MBS whose weight-average molecular weight is 36700and molecular weight distribution is 1.13, and reported that the polymerforms smectic A phase by the observation of small angle X ray structuraldiffraction, space-distance of layers is approximately corresponds tomolecular length, smectic A phase transforms to cholesteric phase withelevation of temperature and reflection of wide angle X ray diffractionbecomes sharp along with the drop of temperature [Liquid Crystal Forum;published on Sep. 27, 2001, No. 3D12, Polymer Forum; held on Sep. 13,2001, No. II 17].

The subject of the present invention is to develop said former study andto provide a process to produce a polymer composition having temperaturedependency of desired circular polarization selective reflection wavelength property easily. On investigating the correlation of the polymercomposition obtained by said observation with liquid crystaltransferring behavior, the inventors of the present invention consideredthat, by observing what liquid crystal property is obtained when thepolymer-fractions fractionated previously are mixed, by previouslycarrying out synthesis of polymer composition and fractionating thesynthesized polymer composition, a polymer composition which meets tothe requirement of the liquid crystal property can be obtained by simplymixing above mentioned fractionated polymers. Accordingly, the inventorsof the present invention blended the polymer-fractions fractionatedpreviously, observed the liquid crystal property of the blendedcomposition and found out, for example, that the compound of liquidcrystal property having temperature dependency of desired circularpolarization selective reflection wave length property can be obtainedwith good reproducibility, thus the subject of the present inventioncould be dissolve.

SUMMARY OF THE INVENTION

The present invention is a process to produce a polymer liquidcrystalline composition having temperature dependency of desiredcircular polarization selective reflection wave length property by onlymixing two or more kinds of starting materials obtained by fractionationhaving different weight-average molecular weight comprising, mixing twoor more kinds of rigid rodlike helical polymers with chiral side chainshaving different weight-average molecular weight synthesized from samemolecule and with same repeating unit whose molecular weightdistribution indicated by the ratio of weight average molecularweight/number average molecular weight is from 1.00 to 1.25, andcontrolling weight average molecular weight, number average molecularweight and molecular weight distribution by mixing ratio.

Desirably, the present invention is a process to produce a polymerliquid crystalline composition which shows temperature dependency ofdesired circular polarization selective reflection wave length propertyby thermo-tropic liquid crystalline phase by only mixing two or morekinds of starting materials whose weight average molecular weight aredifferent.

In above mentioned inventions, the present invention is the process toproduce a polymer liquid crystalline composition having temperaturedependency of desired circular polarization selective reflection wavelength property by only mixing two or more kinds of starting materialshaving different weight-average molecular weight whose molecular weightdistribution and weight average molecular weight are previously fixedcomprising, the polymer compositions having two or more kind ofdifferent weight average molecular weight, which are polymerssynthesized from molecules whose rigid rodlike helical repeating unithaving chiral side chain with fixed molecular weight distribution andweight average molecular weight, wherein said polymer composition is thepolymer having a repeating unit represented by following general formulaA.

[in general formula A, R¹ and R² are the groups selected independentlyfrom alkyl group of carbon number 2-22 or alkyl group of carbon number2-22 having aryl group at the end, R³ is a chiral alkyl group havingbranch structure at β site, R* is a chiral alkyl group having branchstructure at α site, β site (or γ site), left-handed (S) and/orright-handed (R) and when (S) and (R) are existing together with, atleast 1% of either is contained. m≧0, (n+m)≧0.01]

Desirably, the present invention is the process to produce a polymerliquid crystalline composition having temperature dependency of desiredcircular polarization selective reflection wave length property by onlymixing two or more kinds of starting materials having differentweight-average molecular weight whose molecular weight distribution andweight average molecular weight are previously fixed, wherein theweight-average molecular weight of the polymers to be mixed is from10000 to 100000.

BRIEF ILLUSTRATION OF THE DRAWINGS

FIG. 1 shows the GPC elution curve of fractionated sample Fr11 (a)mentioned in Table 1 and GPC elution curve of fractionated sampleprepared by mixing Fr10 to fractionated sample 11 by mixing ratio of 7:3(b).

FIG. 2 shows the temperature dependency of circular dichroism selectivereflection spectrum of fractionated sample Fr11 (a) mentioned in Table 1and the temperature dependency of circular dichroism selectivereflection spectrum of mixed specimen prepared by mixing fractionatedsample Fr11 and Fr10 by mixing ratio of 7:3 (b). Since vertical axis andelliptic modulus are in proportion to the thickness of the specimen,arbitrary number is used.

FIG. 3 shows the GPC elution curve of specimen prepared by mixingfractionated sample Fr11 and Fr9 mentioned in Table 1 by mixing ratio of7:3.

FIG. 4 shows the temperature dependency of circular dichroism spectrumof specimen prepared by mixing fractionated sample Fr11 and Fr9mentioned in Table 1 by mixing ratio of 7:3. Since vertical axis andelliptic modulus are in proportion to the thickness of the specimen,arbitrary number is used.

FIG. 5 shows the temperature dependency of the peak wave-length ofcircular dichroism selective reflection spectrum at each temperature offractionated sample Fr11 (●) mentioned in Table 1, specimen prepared bymixing fractionated sample Fr11 and Fr10 by mixing ratio of 7:3 (◯) andspecimen prepared by mixing fractionated sample Fr11 and Fr9 by mixingratio of 7:3 (□).

DESCRIPTION OF THE PREFERRED EMBOBYMENT

A. Production of Polymer Compositions and Fractionated Polymers Used inthe Present Invention.

(1) Synthesis of n-decyl-(S)-2-methylbutyldichlorosilane, which is theStarting Material Polymer.

3.9 g (0.16 mol) of magnesium was contained into a dry 300 mLthree-necked flask and replaced by argon gas. 50 mL of tetrahydrofurane(hereinafter shortened to THF) was added and heated to 70° C. Then smallamount of dibromobutane was added and stirred so as to activate thesurface of magnesium. 14.3 g (0.13 mol) of 1-chloro-(S)-2-methylbutanewas dropped by a dropping funnel and stirred for 2 hours. Then cooleddown to room temperature and Grignard reagent was obtained.

After that, THF (50 mL) and 44.25 g (0.16 mol) of n-decyltrichlorosilanewere poured into a dry 300 mL three-necked flask. The temperature waselevated to 60° C. and the obtained THF solution of Grignard reagent wasdropped in it slowly. The obtained product was pressed, filtrated and33.26 g of crude product was obtained, then was distilled andfractionated by a vacuum distillater (0.8 mHg) utilizing the differenceof boiling point of dichlorosilane [100° C. (0.8 mHg)] which is thesubjected product and that of trichlorosilane [130° C. (0.8 mHg)] whichis the starting material.

(2) Synthesis of Polysilane

Inside of 500 mL three-necked flask, which is a reacting vessel wasdegassed well and replaced by argon gas. 18-crown ether-6 (34.0 mg) wascontained in said reacting vessel and heated to 120° C. (on oil bath).0.3 g (12.84 mmol) of sodium metal and 50 mL of dehydrated toluene wereadded into the reacting vessel and 2.0 g (6.42 mmol) of startingmaterial monomer was dropped slowly with constant stirring. Whenviscosity became high, viscosity was reduced by adding dehydratedtoluene. After stirring for 2 hours, reacted mixed solution wasfiltrated by pressing. A polymer before purification was a bimodalpolymer having peaks at approximately 80 and 50000 of molecular weight.

(3) Fractionation of Polymer

To the toluene solution of polymer after all synthesis processes werecompleted, small amount of isopropylalcohol was added and from the highmolecular weight components were precipitated. Generated precipitationwas centrifuged, filtrated by press filtration and dried by vacuumdrying so as to obtain a fractionated sample. By repeating same processon residue solution, from higher molecular weight fraction to lowermolecular weight fraction was fractionated in order. The solvent to beadded was changed in order from isopropylalcohol to ethanol, to methanoland to water in connection with polymer molecular weight fractionated.Fractions obtained by said fractionation process are summarized inTable 1. TABLE 1 Fraction (Fr) Mw Mn Mw/Mn Fr1 505300 183300 2.76 Fr2149300 127700 1.17 Fr3 96100 85500 1.13 Fr4 76600 69700 1.10 Fr5 6360058800 1.08 Fr6 49000 44800 1.09 Fr7 38500 35699 1.08 Fr8 31700 297001.07 Fr9 25500 24000 1.06  Fr10 20900 19700 1.06  Fr11 11100 10000 1.11

EXAMPLE

The present invention will be illustrated more in detail according tothe following Examples. However, these Examples are intending to makeobvious the usefulness of the present invention and not intending tolimit the scope of the claims of the present invention.

Measuring condition;

-   GPC: Product of Waters, 150-Ctype, Gel osmotic chromatography-   Circular dichroism measurement: Product of Nihon Bunko Co., Ltd.,    J-720WI circular dichroism scattring meter

Example 1

Liquid crystal properties of polymer composition obtained by mixing ofsaid fractionated fractions;

GPC elution curves of fractionated sample Fr11, which is in Table 1, andspecimen prepared by mixing this Fr11 with Fr10 by mixing ratio of 7:3are shown in (a) and (b) in FIG. 1. Weight average molecular weight ofthe specimen becomes (Mw)=13700, Mw/Mn=1.18 by mixing and accordinglymolecular weight distribution is relatively broadened.

FIG. 2(a) shows the temperature dependency of circular dichroismselective reflection spectrum of fractionated sample Fr11 and FIG. 2(b)shows the temperature dependency of circular dichroism reflectionspectrum of mixed specimen prepared by mixing fractionated sample Fr11and Fr10 by mixing ratio of 7:3. When compared by same measuringtemperature, it is obvious that the peak wave-length of circulardichroism selective reflection spectrum shifts to longer wave-lengthregion by mixing of Fr10 to Fr11. From this fact, it is understood thatthe specimen having a desired circular polarization selective reflectionproperty can be produced by mixing different fractions. And, it can bepredicted that the circular polarization selective reflection propertycan be adjusted by adjusting mixing ratio of different fractions.Further, it can be easily predicted that such property generates whenmixing fraction is changed.

Example 2

FIG. 3 shows the GPC elution curve of specimen prepared by mixingfractionated sample Fr11 and Fr9 mentioned in Table 1 by the mixingratio of 7:3. Weight average molecular weight of the mixed specimenbecomes (Mw)=16600, Mw/Mn=1.26 by mixing and molecular weightdistribution is broadened along with the increase of the difference ofmolecular weight of the mixed 2 specimens.

FIG. 4 shows the temperature dependency of circular dichroism spectrumof a specimen prepared by mixing preparative specimen Fr11 and Fr9mentioned in Table 1 by the mixing ratio of 7:3. When compared withcircular dichroism spectrum (CD) [(b) of FIG. 2] of mixture of Fr11 andFr10 by 7:3 mixing ratio, the peak wave-length of circular dichroismreflection spectrum is more remarkably shifted to longer wave-lengthside, and it is clear that there is strong correlation between adjustedmolecular weight and shifting value of circular polarization selectivereflection wave-length of cholestric liquid crystal phase.

The peak wave-length of circular dichroism selective reflection spectrumof fraction Fr11, specimen prepared by mixing Fr11 and Fr10 by themixing ratio 7:3 and specimen prepared by mixing Fr11 and Fr9 by mixingratio 7:3 are shown in FIG. 5. Correlation of adjusted molecular weightwith shifting value of circular polarization selective reflectionwave-length of cholestric liquid crystal phase can be observed moreclearly. From this fact, it is understood that the specimen havingdesired circular polarization selective reflection spectrum can beproduced by adjusting molecular weight by mixing.

INDUSTRIAL APPLICABILITY

As mentioned above, by the present invention, following excellent effectcan be expected. That is, by previously separating rigid rodlike helicaloptical active organic polymers having chiral side chains to componentswhose molecular weight distribution indicated by ratio of weight averagemolecular weight/number average molecular weight is in the range frommore than 1.00 to less than 1.25 and having different weight averagemolecular weight, the polymer composition whose liquid crystallinitywhich shows desired properties, especially phase transfer temperatureand temperature dependency of optical property are optionally adjustedcan be obtained by mixing 2 or more above mentioned separatedcomponents. Further, by using the said liquid crystal property, theexcellent effect, for example, molecular devices, for example, opticaldevice, memory material or recognition sensor for chemical substancescan be produced simply and by low cost without using a large-sizemanufacturing facility, can be accomplished.

1. A process to produce a polymer liquid crystalline composition havingtemperature dependency of desired circular polarization selectivereflection wave length property by only mixing two or more kinds ofstarting materials obtained by fractionation having differentweight-average molecular weight comprising, mixing two or more kinds ofrigid rodlike helical polymers with chiral side chains having differentweight-average molecular weight synthesized from same molecule and withsame repeating unit whose molecular weight distribution defined by theratio of weight average molecular weight/number average molecular weightis from 1.00 to 1.25, and controlling weight average molecular weight,number average molecular weight and molecular weight distribution bymixing ratio.
 2. A process to produce a polymer liquid crystallinecomposition which shows temperature dependency of desired circularpolarization selective reflection wave length property by thermo-tropicliquid crystalline phase by only mixing two or more kinds of startingmaterials obtained by fractionation whose weight average molecularweight are different.
 3. The process to produce a polymer liquidcrystalline composition having temperature dependency of desiredcircular polarization selective reflection wave length property by onlymixing two or more kinds of starting materials having differentweight-average molecular weight whose molecular weight distribution andweight average molecular weight are previously fixed comprising, thepolymer compositions having two or more kind of different weight averagemolecular weight, which are polymers synthesized from molecules whoserigid rodlike helical repeating unit having chiral side chain of claim2, wherein said polymer composition is the polymer having a repeatingunit represented by following general formula A,

wherein, R¹ and R² are the groups selected independently from alkylgroup of carbon number 2-22 or alkyl group of carbon number 2-22 havingaryl group at the end, R³ is a chiral alkyl group having branchstructure at β site, R* is a chiral alkyl group having branch structureat α site, β site or γ site, left-handed (S) and/or right-handed (R) andwhen (S) and (R) are existing together with, at least 1% of either iscontained, m≧0 and n+m≧0.01.
 4. The process to produce a polymer liquidcrystalline composition having temperature dependency of desiredcircular polarization selective reflection wave length property by onlymixing two or more kinds of starting materials having differentweight-average molecular weight whose molecular weight distribution andweight average molecular weight are previously fixed of claim 3, whereinthe weight-average molecular weight of the polymers to be mixed is from10000 to
 100000. 5. The process to produce a polymer liquid crystallinecomposition having temperature dependency of desired circularpolarization selective reflection wave length property by only mixingtwo or more kinds of starting materials having different weight-averagemolecular weight whose molecular weight distribution and weight averagemolecular weight are previously fixed comprising, the polymercompositions having two or more kind of different weight averagemolecular weight, which are polymers synthesized from molecules whoserigid rodlike helical repeating unit having chiral side chain of claim1, wherein said polymer composition is the polymer having a repeatingunit represented by following general formula A,

wherein, R¹ and R² are the groups selected independently from alkylgroup of carbon number 2-22 or alkyl group of carbon number 2-22 havingaryl group at the end, R³ is a chiral alkyl group having branchstructure at β site, R* is a chiral alkyl group having branch structureat α site, β site or γ site, left-handed (S) and/or right-handed (R) andwhen (S) and (R) are existing together with, at least 1% of either iscontained, m≧0 and n+m≧0.01.
 6. The process to produce a polymer liquidcrystalline composition having temperature dependency of desiredcircular polarization selective reflection wave length property by onlymixing two or more kinds of starting materials having differentweight-average molecular weight whose molecular weight distribution andweight average molecular weight are previously fixed of claim 5, whereinthe weight-average molecular weight of the polymers to be mixed is from10000 to
 100000. 7. The process to produce a polymer liquid crystallinecomposition having temperature dependency of desired circularpolarization selective reflection wave length property by only mixingtwo or more kinds of starting materials having different weight-averagemolecular weight whose molecular weight distribution and weight averagemolecular weight are previously fixed of claim 1, wherein theweight-average molecular weight of the polymers to be mixed is from10000 to 100000.